1. Field
The present embodiments relate to a dendrimer and an organic light-emitting device including an organic layer having the dendrimer.
2. Description of the Related Technology
An organic light-emitting device includes an anode, a hole transport layer, an emission layer, an electron transport layer and a cathode, which are sequentially formed on a substrate. In this regard, the hole transport layer, the emission layer, and the electron transport layer are thin films comprising organic compounds.
An organic light-emitting device is a self-emitting device in which when a current is applied to a fluorescent or phosphorescent organic layer, electrons are combined with holes in the organic layer, thereby emitting light. Since organic light-emitting devices are lightweight, can be fabricated using simple constituent elements in an easy fabrication process, can realize superior image quality, high color purity, and dynamic images, and operate with low power consumption, diverse research is being conducted into organic light-emitting devices. An organic light-emitting device may include a hole-related layer such as a hole injection layer and a hole transport layer and an electron-related layer such as an electron transport layer and an electron injection layer in addition to an organic emission layer between an anode and a cathode.
Organic light-emitting devices may be manufactured using a deposition or wet process. In general, an organic material having a molecular weight of 1,000 or less is suitable for the deposition process. It is well known that an organic light-emitting device manufactured using a low-molecular weight compound such as a fluorene-based compound by using a deposition process has excellent luminance. However, if an organic light-emitting device is manufactured using a low-molecular weight compound for deposition (such as a fluorene-based compound) by using a wet process, various problems, for example, crystallization during a drying process after forming a layer may occur. When crystallization is initiated, a start point, as a seed, extends to form a dark spot in the organic light-emitting device. In order to prevent this crystallization, a large-size substituent or a substituent that is not crystallized may be introduced, or an organic material having a molecular weight of about several thousands may be used to inhibit alignment or arrangement of molecules. A dendrimer or a polymer may be used in order to increase the molecular weight of the organic material.
Since synthesis and purification of a polymer are difficult and the polymer has diverse molecular weights, it is difficult to regulate physical properties, such as energy level and thermal characteristics, which determine emission characteristics. However, synthesis and purification of a dendrimer are relatively easier than those of the polymer and the dendrimer is a single compound of which the molecular structure is easy to control, and thus physical properties thereof which affect characteristics of an organic light-emitting device may be regulated.
Therefore, there is need to develop an organic light-emitting device using a dendrimer.